easejs/doc/about.texi

@c  This document is part of the GNU ease.js manual.
@c  Copyright (C) 2011, 2013, 2014 Mike Gerwitz
@c    Permission is granted to copy, distribute and/or modify this document
@c    under the terms of the GNU Free Documentation License, Version 1.3 or
@c    any later version published by the Free Software Foundation; with no
@c    Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts.
@c    A copy of the license is included in the section entitled ``GNU Free
@c    Documentation License''.

@node About
@unnumbered About GNU ease.js

GNU ease.js is a classical object-oriented framework for Javascript,
intended to eliminate boilerplate code and ``ease'' the transition into
JavaScript from other object-oriented languages.

Current support includes:
@itemize @bullet
@item Simple and intuitive class definitions
@item Classical inheritance
@item Abstract classes and methods
@item Interfaces
@item Traits as mixins
@item Visibility (public, protected, and private members)
@item Static, constant, and final members
@end itemize

While the current focus of the project is Object-Oriented design, it is
likely that ease.js will expand to other paradigms in the future.


@section History
ease.js was initially developed for use at the author's place of employment
in order to move the familiar concept of object-oriented development over to
JavaScript for use in what would one day be liberated under the
@uref{https://github.com/lovullo/liza,Liza Data Collection Framework}.
JavaScript lacks basic core principals of object-oriented development, the
most major of which is proper encapsulation.

The library would be required to work both server and client-side,
supporting all major web browsers as far back as Internet Explorer 6. Since
it would be used in a production system and would be used to develop a core
business application, it must also work flawlessly. This meant heavy unit
testing.

The solution was to develop a library that would first work server-side. The
software of choice for server-side JavaScript was @uref{http://nodejs.org,
Node.js}. Node uses the CommonJS format for modules. This provided an
intuitive means of modularizing the code without use of an Object Oriented
development style (the closest other option would be Prototypal). ease.js
was first developed to work on Node.js.

Moving the code over to the browser is not a difficult concept, since the
entire library relied only on standard JavaScript. A couple important
factors had to be taken into account, mainly that CommonJS modules don't
simply ``work'' client-side without some type of wrapper, not all browsers
support ECMAScript 5 and the assertion system used for tests is a Node.js
module.

This involved writing a simple script to concatenate all the modules and
appropriately wrap them in closures, thereby solving the CommonJS issue. The
required assertions were ported over to the client. The only issue was then
ECMAScript 5 support, which with a little thought, the browser could
gracefully fall back on by sacrificing certain features but leaving the core
functionality relatively unscathed. This provides a proper cross-browser
implementation and, very importantly, allows the unit tests to be run both
server and client side.  One can then be confident that ease.js will operate
on both the server and a wide range of web browsers without having to
maintain separate tests for each.

Needless to say, the development was successful and the project has been
used in production long before v0.1.0-pre was even conceived. It was thought
at the beginning of the project that versions would be unnecessary, due to
its relative simplicity and fairly basic feature set. The project has since
evolved past its original specification and hopes to introduce a number of
exciting features in the future.

The project is owned and developed independently by Mike Gerwitz. There is
no ownership by his employer.

On 22 December 2013, ease.js officially became a part of GNU with the kind
help and supervision of Brandon Invergo.


@section Why ease.js?
There already exists a number of different ways to accomplish inheritance
and various levels of encapsulation in JavaScript. Why ease.js? Though a
number of frameworks did provide class-like definitions, basic inheritance
and other minor feature sets, none of them seemed to be an all-encompassing
solution to providing a strong framework for Object-Oriented development in
JavaScript.

ease.js was first inspired by John Resig's post on ``Simple JavasScript
Inheritance''@footnote{John's blog post is available at
@uref{http://ejohn.org/blog/simple-javascript-inheritance/}.}. This very
basic example provided a means to define a ``class'' and extend it. It used
a PHP-style constructor and was intuitive to use. Though it was an excellent
alternative to defining and inheriting classes by working directly with
prototypes, it was far from a solid solution. It lacked abstract methods,
interfaces, encapsulation (visibility), and many other important features.
Another solution was needed.

Using John's example as a base concept, ease.js was developed to address
those core issues. Importantly, the project needed to fulfill the following
goals:

@table @strong
@item Intuitive Class Definitions
Users of Object-Oriented languages are used to a certain style of class
declaration that is fairly consistent. Class definitions within the
framework should be reflective of this. A programmer familiar with
Object-Oriented development should be able to look at the code and clearly
see what the class is doing and how it is defined.

@item Encapsulation
The absolute most important concept that ease.js wished to address was that
of encapsulation. Encapsulation is one of the most important principals of
Object-Oriented development. This meant implementing a system that would not
only support public and private members (which can be done conventionally in
JavaScript through ``privileged members''), but must also support
@emph{protected} members. Protected members have long been elusive to
JavaScript developers.

@item Interfaces / Abstract Classes
Interfaces and Abstract Classes are a core concept and facilitate code reuse
and the development of consistent APIs. They also prove to be very useful
for polymorphism. Without them, we must trust that the developer has
implemented the correct API. If not, it will likely result in confusing
runtime errors.  We also cannot ensure an object is passed with the expected
API through the use of polymorphism.

@item Inheritance
Basic inheritance can be done through use of prototype chains. However, the
above concepts introduce additional complications. Firstly, we must be able
to implement interfaces. A simple prototype chain cannot do this (an object
cannot have multiple prototypes). Furthermore, protected members must be
inherited by subtypes, while making private members unavailable. In the
future, when traits are added to the mix, we run into the same problem as we
do with interfaces.

@item CommonJS, Server and Client
The framework would have to be used on both the server and client.
Server-side, @uref{http://nodejs.org, Node.js} was chosen. It used a
CommonJS format for modules. In order to get ease.js working client side, it
would have to be wrapped in such a way that the code could remain unchanged
and still operate the same. Furthermore, all tests written for the framework
would have to run both server and client-side, ensuring a consistent
experience on the server and across all supported browsers. Support would
have to go as far back as Internet Explorer 6 to support legacy systems.

@item Performance
Everyone knows that Object-Oriented programming incurs a performance hit in
return for numerous benefits. ease.js is not magic; it too would incur a
performance it. This hit must be low. Throughout the entire time the
software is running, the hit must be low enough that it is insignificant
(less than 1% of the total running time). This applies to any time the
framework is used - from class creation to method invocation.

@item Quality Design
A quality design for the system is important for a number of reasons. This
includes consistency with other languages and performance considerations. It
must also be easily maintainable and extensible. Object-Oriented programming
is all about @emph{restricting} what the developer can do. It is important
to do so properly and ensure it is consistent with other languages. If
something is inconsistent early on, and that inconsistency is adopted
throughout a piece of software, fixing the inconsistency could potentially
result in breaking the software.

@item Heavily Tested
The framework would be used to develop critical business applications. It
needed to perform flawlessly. A bug could potentially introduce flaws into
the entire system. Furthermore, bugs in the framework could create a
debugging nightmare, with developers wondering if the flaw exists in their
own software or the framework. This is a framework that would be very
tightly coupled with the software built atop of it. In order to ensure
production quality, the framework would have to be heavily tested. As such,
a test-driven development cycle is preferred.

@item Well Documented
The framework should be intuitive enough that documentation is generally
unneeded, but in the event the developer does need help in implementing the
framework in their own software, the help should be readily available.
Wasting time attempting to figure out the framework is both frustrating and
increases project cost.

@end table

The above are the main factors taken into consideration when first
developing ease.js. There were no existing frameworks that met all of the
above criteria.  Therefore, it was determined that ease.js was a valid
project that addressed genuine needs for which there was no current,
all-encompassing solution.